Cylinder construction



Aug. 20, 1946. "R. PLPE SCARA I 2,406,100

CYLINDER CONSTRUCTION Filed April 6, 1944 III 2 21 2.5 B0 5' v- INVENTOR J76 Raal'ikzemyfiescara Patented Aug. 20 1946 UNITED" STATES PATENT OFFICE Raul Pateras Pescara, Lisbon, Portugal Application April 6, 1944, Serial No. 529,829 In France August 6, 1943 14 Claims.

My invention relates to the cylinders of opposed piston engines, i. e; of engines comprising one or several pairs of pistons slidable in opposed relation within one and the same cylinder for each pair, and it refers more particularly to the cylinders of free-piston engines, which have to withstand very high pressures.

In such engines, it is known to make the cylinder in three parts, viz. a central member forming part of the combustion chamber of the engine and made of a suitable material to withstand high temperatures and pressures, and two lateral members in co-axial relation with the said central member, such lateral members housing the pistons and being so disposed as to ensure a satisfactory mechanical and thermic working (with respect to friction and cooling) My invention has for its object :to" provide means whereby in such cylinders the lateral members may be assembled with the central member and it consists primarily in so arranging such means that they give rise to a radial inward pressure on the inner ends of the lateral members, thus acting on said ends as a shrunk ring, at least when the cylinder parts are at their normal operative temperatures.

In the annexed drawing:

Fig. 1 i a longitudinal diagrammatical section of an engine provided with a, cylinder established in accordance with my invention, f

Figs. 2 to 4 are partialviews to an enlarged scale showing in section three embodiments of my invention.

In Fig. l, the engine shown is a free-piston engine of the opposed'piston type. It comprises i a cylinder made of three parts I, 2 and 3, and a pair of pistons 4 and 5 operating therein. This cylinder is provided .with inlet ports 6 and exhaust ports I, and with cooling-jackets 8, 9 and I0. The engine also comprises means to ensure the return stroke of the pistons, means to synchronise their motion and means to inject fuel in the space comprised between them when they are at their inner dead point or in in the-vicinity thereof. Such arrangements are well-knownin engines of this kind and need not be described here, since they form no part of this invention.

The central member I of cylinder I, 2,3 is ringshaped and is adapted to. form the combustion chamber of the engine, or at least the major part thereof. It may be made of steel, for instance. The lateral members 2 and 3 are disposed each sideof member I and in co-axial relation therewith. They are adapted to receive the pistons for this purpose; Member I may be made relatively thick to withstand the high pressures which take place within the combustion chamber, while members 2 and 3 are thinner inorder to facilitate cooling. Ports I are provided in member 2 While ports are provided in member'3.

Cooling jackets 8 a d 9 are preferably disposed, as shown, at the outer ends of members 2 and 3, corresponding to the outer dead points of pistons 4 and 5, while the intermediate jacket I0 is formed by annular partitions II, I2, for instance circular, supported by members I and 2, such partitions being tightly jointed, as shown at I3 in'Fig. 2, with an outer tubular casing I4. Joints I3 may be made of rubber, for instance. Jacket Iii, thus formed, may be filled with cooling liquid and it may communicate with jackets 8 and 9for liquid circulation purposes. I

On the inlet side of cylinder I, 2, 3, partition II is disposed between inlet ports 5 and. the inner end of member 2. On the outlet side, partition I2 is also arranged between outlet ports I and the inner end of member 3, but there is preferably provided another partition I5 on the other side of ports I, the space comprised between partitions I2 and I5 being closed at its periphery to form an exhaust gas collector I6.

Ifhe outer contour of cylinder I, 2, 3 (i. e. the outer diameter of partitions II, I2 and I5) is such ing I4 wherein it is fixed by any appropriate means not shown.

Members I, 2 and 3 are assembled together by means ensuring axial pressure of members 2 and 3 against member I, such means being such that they also ensure radial inward pressure on the inner ends of members 2 and 3, at least when the parts are at their normal operative temperature corresponding to normal engine operation,

This may be obtained,.for instance, by means of appropriate conical surfaces, as shown in Fig. 4, provided on the ends of members I, 2 and 3, such surfaces being so disposed that the axial pressure (obtained by'bolts, for instance) gives rise to a radial inward pressure on the end of member 2 and 3.

In the construction shown in Fig. 2, members 2 and I abut against each other through plane surfaces transverse with respect to the cylinder axis and they are assembled by means of a crown I! which is pressed towards member I by means of nuts I8, such crown acting on a shoulder 20a of a collar 20 formed at the end of member 2. Crown I'I is'made of a material having alow 4 and 5 and are made of an appropriate metal coefficient of expansion audit is arranged'to' fit that the cylinder as a whole may be slid into cas-' collars formed at their 3 radially on member 2 on which it'thus acts as a shrunk ring when the temperature rises. For this purpose, it is provided on its inner surface with recesses I9 forming passage for the cooling fluid between said ring and the outer surface of member 2. And crown I! preferably acts on the end collar formed on member 2 through an intermediate ring 2 I, as shown. Ring 2| is cut into two halves; it is rectangular in cross-section and fits without play in the annular space provided on the one hand between I I shoulders Na and 20a of crown I! and collar 2!! respectively, and on the other hand between the cylindrical surfaces Nb and 20b of said crown I! and collar 20 respectively. Ring 2! thus transmits to collar 20 the axial pressure exerted by nuts I8 and also the radial inward pressure re-- sulting from the lower expansion of crown I i when the cylinder is hot. And when ring 2I is removed after nuts I8 have been removed, crown I! can be withdrawn, since its inner diameter is larger than the outer diameter of collar 20.

The outer diameter of crown IIfis such that it does not prevent the cylinder I, 2, 3 from being slid into casing I4.

In the modified construction shown in Fig. 3,

the liquid passages I9 are provided in collar 23 instead of being cut in crown I1. a I

In the construction shown in Fig. 4, members 2 and I abut. against each other through a conical surface 22, the apex of the cone being disposed towards member I." Ring ZI is wedge-shaped and it bears against collar 20 through an oblique or conical surface 23., the apex of thecone being situated towards. the outer end of member 2. It will readily be understood that the tightening of nuts I8 gives rise to a radial inward pressure on collar 2B,even in the cold state, such pressure increasingwhen the cylinder reaches its operative temperature.

With any of the above-described arrangements, the inner ends of the lateral members 2 and 3 are firmly maintained against the action of high member having inward conical end faces, said 7 central member being adapted to form part of the engine combustion chamber; two tubular lateral members co-axial with said central member and disposed each side thereof,- said lateral members having outward conical end faces corresponding to and in'contact with said inward conical faces; and means to press axially said lateral members against said central member.

3. A cylinder for an opposed-piston engine, comprising in combination a central annular member adapted to form part of the engine combustion chamber-y two tubular lateral members co-axial with said central member and disposed each side thereof, said lateral members having inner ends; crowns adapted to fit radially onlsaid lateral members and to'abut axially, against. said collars; and

I 4 means to press said crowns towards said central member.

4. A cylinder as claimed in claim 3, wherein said crowns are made of a material having a lower coefficient of thermal expansion than said lateral members.

5. A cylinder for an opposed-piston engine, comprising in combination a central annular member adapted to form part of the engine combustion chamber, two tubular lateral members co-v ameter of the corresponding collar; two crowns adapted to fit radially on one and the other of said split rings to press same radially against said lateral members, said crowns being shouldered inwardly, the shoulder having an inner diameter larger than the outer diameter of thecorresponding collar, but smaller than the outer diameter of the corresponding split ring and being so disposed as to abut axially against said split ring .to press same towards said central member; and means to press said crowns towards said centralmemberl 6. A cylinder as claimed in claim 5,, wherein said crowns are made of a material having a lower coefficient of thermal expansion than said lateral members. r

7. A cylinder as claimed in Claim 5, wherein recesses are provided in said crowns to formcooling fluid passages between said crowns and said split rings. V I

8. A cylinder as claimed in claim 5, wherein recesses are provided in said lateral members. to

form cooling fluid passages between said sp it rings and said lateral members.

A y n f r n pposed-piston en ine co p ising in combination a cen ral annular member adapted to form art of the en ine combustion chamber, said entral member havin inwardly conical end faces; two tubular lateral members co-axial with said central member and disposed each sidethereof,; saidlateral members having collars formed at their inner ends, and each of. said collars having an inner endand an outer outwardly conical end face, the outeronecf said outwardly conical end faces being adapted to fit into the correspondinginwardlyconical end face of said central member; two'split rings adapted to be passed over said collars, each of said split rings having an inwardly conical face adapted to fit on the outer outwardly conical end face of the corresponding collar, and each of said split rings having an outer diameter larger'than theouter diameter of the corresponding collar;

two crowns adapted to fit radially on one and the l0- A cy nderas cl imed. n claim v 9 wherein said crowns are made of a material having a lower coefficient of thermal expansion than said lateral members.

11. A cylinder as claimed in claim 9, wherein recesses are provided in said crowns to form cooling fluid passages between said crowns and said split rings.

12. A cylinder as claimed in claim 9, wherein recesses are provided in said lateral members to form cooling fluid passages between said split rings and said lateral members.

13. A cylinder for an opposed-piston engine which comprises, in combination, a central annular member adapted to form at least 'part of the engine combustion chamber, two tubular lateral members co-axial with said central member 10- cated on either side thereof respectively, two ringshaped members adapted to fit radially respectively on one and the other of said lateral members in the vicinity of the inner ends thereof, means for maintaining, underoperative conditions, said ring-shaped members at a temperature lower than that of the adjacent portions of said lateral members, and means for axially pressing said lateral members against said central member.

14. A cylinder according to claim 13 in which said ring-shaped members are made of a material having a lower coefllcient of therma1 expansion than said lateral members.

RAUL PATERAS PESCARA. 

